In an elevating mechanism of this kind, known from U.S. Pat. No. 3,711,054, the generally cylindrical other surface of the gas spring housing is guided directly in a guide sleeve connected with the guide tube. Not only is the gas spring supporting and length-adjustable, but it also is a guiding and pivotable element. Because the piston rod is fastened in the base plate of the guide tube not just freely pivotable, but also radially with sufficient free play, the gas spring can adjust to possible changes in the direction of stress of the seat or the table top without danger of jamming. Furthermore, the seals around the piston rod of the gas spring are not unilaterally stressed, so that the gas spring will not become leaky and therefore inoperational. Thus the gas spring is cushioned on its sides with respect to the tube-like column, so that jamming neither occurs between piston rod and cylinder nor between cylinder and the tube-like column.
Lockable elevating mechanisms of this kind have proven themselves in actual operation for a long time and to a large degree.
The attachment of the gas spring housing on the underside of the seat or table top is accompanied by means of a clamping device comprising a cylindrical upper section of the gas spring housing, such as is known from U.S. Pat. No. 3,711,054 or 4,283,033, for instance. It is furthermore known to equip the gas spring with a conical attachment section for the purpose of providing a connection between the gas spring housing and the underside of the chair seat or the table top, which is inserted by force into a corresponding collar on the underside of the chair seat or the table top. The advantage of this embodiment is to make a connection between the chair seat or table top and the elevating mechanism very easy, which is of special advantage in the case of the shipment of such furniture while disassembled and the subsequent reassembly by the seller
or buyer. Such a conical embodiment of the attachment is known from the U.S. Pat. No. 3,790,119. However there is the danger in such conical plug connections that the attachment section and the corresponding collar will seize because of the constant loads and therefore will no longer be separated, especially not without the use of tools, by which the upper surface of the gas spring housing, which is movable in respect to the guide tube, can be damaged.